Resin for pigment dispersion

Abstract

This invention relates to the use of a copolymer of polymerizable unsaturated monomer containing at least one kind of ionic functional group selected from the group consisting of quaternary ammonium salt group and sulfonic acid group, nonionic polymerizable unsaturated monomer having polyoxyalkylene chain, and other ethylenically unsaturated monomer, as a pigment dispersing resin for water-based paint or water-based ink.

1. Water-based pigment dispersion which comprises a pigment dispersing resin, pigment and aqueous medium, said resin being a copolymer of:
 A) polymerizable unsaturated monomer containing at least one quaternary ammonium salt group; 
 B) nonionic polymerizable unsaturated monomer having polyoxyethylene chain; and 
 C) other ethylenically unsaturated monomer, wherein the copolymer is produced by the copolymerization of 1 to 15% by weight of quaternary ammonium salt group-containing polymerizable unsaturated monomer (A), 5 to 40% by weight of nonionic polymerizable unsaturated monomer (B) and 45 to 94% by weight of other ethylenically unsaturated monomer (C) on the basis of the total weight of monomers (A), (B) and (C). 
 
     
     
       2. A water-based coating composition which comprises the water-based pigment dispersion of  claim 1 . 
     
     
       3. A water-based coating composition of  claim 2  which is top-coating coloring paint for automobile. 
     
     
       4. An article which has been coated with the water-based coating composition of  claim 2 . 
     
     
       5. A water-based ink composition which comprises the water-based pigment dispersion of  claim 1 . 
     
     
       6. The water-based ink composition of  claim 5  which is ink for ink-jet printer. 
     
     
       7. A print which has been printed by the water-based ink composition of  claim 5 . 
     
     
       8. The pigment dispersing resin of  claim 1  wherein the quaternary ammonium group-containing polymerizable unsaturated monomer (A) is selected from the group consisting of 2-(methacryloyloxy)ethyl trimethylammonium chloride, 2-(methacryloyloxy)ethyl trimethylammonium bromide, (meth)acryloylaminopropyl trimethylammonium chloride, (meth)acryloylaminopropyl trimethylammonium bromide, tetrabutylammonium(meth)acrylate, trimethylbenzylammonium (meth)acrylate and 2-(methacryloyloxy)ethyl trimethylammonium dimethylphosphate. 
     
     
       9. The pigment dispersing resin of  claim 1  wherein the quaternary ammonium group-containing polymerizable unsaturated monomer (A) is 2-(methacryloyloxy)ethyltrimethylammonium chloride. 
     
     
       10. The pigment dispersing resin of  claim 1  wherein the quaternary ammonium group-containing polymerizable unsaturated monomer (A) comprises a combination of quaternary ammonium salt group-containing polymerizable unsaturated monomer and tertiary amino group-containing polymerizable unsaturated monomer. 
     
     
       11. The pigment dispersing resin of  claim 10  wherein tertiary amino group-containing polymerizable unsaturated monomer is selected from the group consisting of N,N-dialkylaminoalkyl (meth)acrylate and N,N-dialkylaminoalkyl (meth)acrylamide. 
     
     
       12. The pigment dispersing resin of  claim 10  wherein the quaternary ammonium group-containing polymerizable unsaturated monomer (A) comprises a combination of 2-(methacryloyloxy)ethyltrimethylammonium chloride and either N,N-dimethylaminoethyl(meth)acrylate or N,N-diethylaminoethyl(meth)acrylate. 
     
     
       13. The pigment dispersing resin of  claim 1  wherein nonionic polymerizable unsaturated monomer (B) is compound of the following formula (1):                  
 in which 
 R 1  stands for hydrogen or CH 3,    
 R 2  stands for hydrogen or alkyl group having one to four carbon atoms, 
 m is an integer of 4–60, and 
 n is an integer of 2, 
 and wherein oxyalkylene units (C n H 2n O) in the number of m may be the same or different from each other. 
 
     
     
       14. The pigment dispersing resin of  claim 1  wherein nonionic polymerizable unsaturated monomer (B) is polyethylene glycol (meth)acrylate. 
     
     
       15. The pigment dispersing resin of  claim 1  wherein other ethylenically unsaturated monomer (C) contains a hydroxyl group-containing polymerizable unsaturated monomer at least as a part of its component. 
     
     
       16. The pigment dispersing resin of  claim 1  wherein other ethylenically unsaturated monomer (C) contains a carboxyl group-containing polymerizable unsaturated monomer at least as a part of its component. 
     
     
       17. The pigment dispersing resin of  claim 1  wherein the copolymer has a weight average molecular weight within a range of 500 to 100,000.